Scouring and polishing pads for use at home and in various industrial applications are well known in the art. Initially, metal wool, such as steel wool, was widely used for scouring household articles such as pots, pans and the like. Similar scouring and polishing pads made of steel wool strands which have been mated together or interwoven into a mass of filaments have also been employed in the industrial field for the removal of substances from surfaces. The metal wool pads had the advantage of deriving their abrasive characteristics and their scouring action from the relative hardness of the metal. Metal wool pads, and particularly steel wool, however, had several disadvantages, including but not limited to, unsightly oxidation (e.g., rusting), breaking or splintering and inability to retain their form and shape.
In order to overcome those disadvantages, the metal pads were in some instances replaced with nonmetallic scouring pads. Accordingly, several scouring pads utilizing synthetic, organic fibers such as nylon, polypropylene, vinyl chlorides, rayon acetates, and other polyesters were developed. Those pads are relatively stable at temperatures likely to be encountered in household and industrial uses and are resistant to corrosive action of other organic chemicals. Furthermore, they are flexible, reliable and economical. Another advantage of those synthetic organic materials is that they may be formed into monofilaments which can be felted into porous open mats or batts of unusually high loft, springiness and compressibility. Examples of such prior art pads are disclosed in U.S. Pat. No. 5,152,809 issued on Oct. 6, 1992 to Mattesky; U.S. Pat. No. 4,991,362 issued on Feb. 12, 1991 to Heyer, et al.; U.S. Pat. No. 4,078,340 issued on Mar. 14, 1978 to Klecker, et al.; U.S. Pat. No. 3,537,121 issued on Nov. 3, 1970 to McAvoy; U.S. Pat. No. 3,284,963 issued on Nov. 15, 1966 to Lanham, et al.; U.S. Pat. No. 3,112,584 issued on Dec. 3, 1963 to Cameron, and United Kingdom Patent No. 1,010,935 published on Nov. 24, 1965 to Klein.
There are several functional and physical characteristics desirable in a scouring pad: the ability to provide a good abrasive action without scratching the surface being cleaned; an open or loft structure relatively unsusceptible to matting or clogging by material removed in the cleaning process; to be oxidation free (rust-free); sufficient resilience for comfortable handling and conformance to irregular contours in the article to be cleansed; the ability to retain a self-contained supply of a cleaning agent and to minimize the waste of detergent; and sufficient strength to endure the rigors of the cleansing operation, to maintain its structural integrity and to prevent tearing or disintegration thereof.
Prior cleansing pads were disadvantageous in that none of those pads combined the above desirable characteristics in one pad. Another disadvantage was that none of those pads had the appropriate abrasiveness for effecting satisfactory cleaning action without scratching soft metal surfaces (e.g., aluminum, copper or the like) and more delicate surfaces made of an tetraflouroethene homopolymer(e.g., Teflon.TM.) or fine china.
In general, processes for the manufacture of such pads and for impregnating such pads with cleaning composition are known. Such prior art processes typically involve dipping the nonwoven material in a trough containing liquid cleaning composition (generally maintained at a temperature sufficiently high to ensure that the cleaning composition stays liquid, then compressing the nonwoven material to remove excess cleaning composition. Steel wool scouring pads impregnated with cleaning composition are typically formed by a similar manner. A predetermined amount of steel wool is placed in a compression chamber. The chamber is flooded with liquid cleaning composition. The pad is then compressed to remove the excess fluid. Such processes, however, do not provide for accurate control of the amount of cleaning composition retained in the pads and are not generally suitable for mass production of relatively thick nonwoven pads. In addition, the processes tend to be inefficient and wasteful.